Chemical Vapor Deposition (CVD) is a vapor based deposition process commonly used in semiconductor manufacturing including but not limited to the formation of dielectric layers, conductive layers, semiconducting layers, liners, barriers, adhesion layers, seed layers, stress layers, and fill layers. CVD is typically a thermally driven process whereby the precursor flux(es) is pre-mixed and coincident to the substrate surface to be deposited upon. CVD requires control of the substrate temperature and the incoming precursor flux(es) to achieve desired film materials properties and thickness uniformity. Derivatives of CVD based processes include but are not limited to Plasma Enhanced Chemical Vapor Deposition (PECVD), High-Density Plasma Chemical Vapor Deposition (HDP-CVD), Sub-Atmospheric Chemical Vapor Deposition (SACVD), laser assisted/induced CVD, and ion assisted/induced CVD.
As device geometries shrink and associated film thickness decrease, there is an increasing need for improved control of the deposited layers. A variant of CVD that enables superior step coverage, materials property, and film thickness control is a sequential deposition technique known as Atomic Layer Deposition (ALD). ALD is a multi-step, self-limiting process that includes the use of at least two precursors or reagents. Generally, a first precursor (or reagent) is introduced into a processing chamber containing a substrate and adsorbs on the surface of the substrate. Excess first precursor is purged and/or pumped away. A second precursor (or reagent) is then introduced into the chamber and reacts with the initially adsorbed layer to form a deposited layer via a deposition reaction. The deposition reaction is self-limiting in that the reaction terminates once the initially adsorbed layer is consumed by the second precursor. Excess second precursor is purged and/or pumped away. The aforementioned steps constitute one deposition or ALD “cycle.” The process is repeated to form the next layer, with the number of cycles determining the total deposited film thickness. Different sets of precursors can also be chosen to form nano-composites comprised of differing materials compositions. Derivatives of ALD include but are not limited to Plasma Enhanced Atomic Layer Deposition (PEALD), radical assisted/enhanced ALD, laser assisted/induced ALD, and ion assisted/induced ALD.
The purge process typically involves introducing a particular fluid (i.e., a purging or purge gas), such as argon, into the chamber to remove the excess precursor material from the components of the tool, such as the showerhead. Depending on the precursors used, the purge process may be particular difficult and/or time consuming as some precursors have a tendency to “stick” or adhere to the components, particularly those made of aluminum. The invention described herein provides systems and method for improving the efficiency of the purging process used in vapor deposition tools, particularly those used in combinatorial processing.